12-Tungstophosphoric acid (TPA) impregnated on four different supports such as hydrous zirconia, silica, alumina and activated carbon was evaluated as solid acid catalysts for the biodiesel production from low quality canola oil containing upto 20 wt% free fatty acids. The hydrous zirconia supported TPA was found to be the most promising catalyst exhibiting the highest ester yield (y77%). The FTIR, XRD and nitrogen adsorption analysis revealed that the Lewis acid sites generated by the strong interaction of TPA and surface hydroxyl groups of zirconia are responsible for their higher activity. Further, the optimization of reaction parameters was carried out with the most active catalysts i.e. TPA supported hydrous zirconia and it was found that at 200 uC, 1 : 9 oil to alcohol molar ratio and 3 wt% catalysts loading a maximum ester yield of 90 wt% could be obtained. The catalysts were recycled and reused with negligible loss in activity.

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Selective hydrogenolysis of glycerol to propylene glycol was performed using an environmentally friendly hydrotalcite-derived mixed-metal oxide catalyst. The Mg/Al, Zn/Al, Ni/Mg/Al, Ni/Co/Mg/Al, and Cu/Zn/Al mixed-metal oxide catalysts were prepared from their corresponding hydrotalcite precursors having M 2+ /M 3+ compositions over the range of 0.5-3.0. The physicochemical properties of the catalysts were studied by X-ray diffraction (XRD), inductively coupled plasma mass spectrometry (ICP-MS), NH 3 and CO 2 temperatureprogrammed desorption (TPD), and nitrogen adsorption studies. The XRD patterns of pure hydrotalcites exhibited characteristics of hydrotalcite phases, while those of calcined hydrotalcites showed the formation of corresponding metal oxides. The ICP-MS analysis showed agreement between the calculated and actual metal compositions. The prepared catalysts were evaluated for the hydrogenolysis of glycerol to propylene glycol in a Parr reactor. The activity studies indicated a maximum glycerol conversion and selectivity toward propylene glycol in the case of Cu/Zn/Al mixed-metal oxide catalysts. Further, the reaction parameters were optimized with the most active Cu/Zn/Al catalyst, and it was found that at a catalyst concentration of 5% (w/w) of aqueous glycerol, a hydrogen pressure of 200 psig, and 80% glycerol dilution, a maximum glycerol conversion of 52% with 93-94% selectivity toward propylene glycol were obtained.

This review discusses the methods for the removal of dyes from the wastewater effluents. Wastewater effluents contain synthetic dyes which cause a potential hazard to the environment hence these dyes need to remove from the water bodies. The various dye removal techniques are classified into Chemical, Physical, and Biological methods. Physical methods includes adsorption, ion exchange, and filtration/coagulation methods etc. while chemical methods includes ozonisation, Fenton reagent, photo catalytic reactions and biological methods include aerobic degradation, anaerobic degradation, biosorption etc. Adsorption found to be very effective and cheap method among the all available dye removal methods. Dyes from the industrial waste water effluents are effectively separated by using adsorbent such as activated carbon however its cost restricts the use in large scale applications. Experimental studies proved that the effective removal of dyes is obtained using several cheaply available non-conventional adsorbents also. Therefore, studies related to searching for efficient and low cost adsorbents derived from existing resources are gaining importance for the removal of dyes.